Division of labour is the way to more productivity.
In industry, this has been the step from craftmenship to mass production.
How does this compare with full stack developers? The demand for them seems to grow exponentially last years.
However, the full stack itself seems to grow as well. Recently, there is also artificial intelligence – sure the technical guys will build it, too: they are after all the experts. However, saving personal costs on this end might cost your an exponential loss of unleashed productivity because there is no labor division.
Now have a look at the learnings from the 2nd industrial revolution.
“One man draws out the wire, another straights it, a third cuts it, a fourth points it, a fifth grinds it at the top for receiving the head: to make the head requires two or three distinct operations: to put it on is a particular business, to whiten the pins is another … and the important business of making a pin is, in this manner, divided into about eighteen distinct operations, which in some manufactories are all performed by distinct hands, though in others the same man will sometime perform two or three of them.” Adam Smith (1776)
An important difference to a pin factory is however that in software engineering, the productivity between developers can range as 1:10 depending on seniority as quoted by Fred Brooks (“Mythical man month”). Time based billing seems by the way to be rather partly a financially demotivating factor; why should somebody work at speed scaling which cannot be mapped in the salary, or hour rate, if not by a heart commitment?
An argument again building industrial software lines is that this is a loss of creativity, and after all DevOps is for product teams as opposite to project and maintenance teams. However, having interdisciplinary teams does not mean that everybody does same job. And, modern engineers use CAD and sophisticated machines to deliver you electric cars and spaceships – I do not think they consider themselves non-creative.